Pulp process



Oct.27, 1936. i A. HocHE PULP PROCESS Original Filed Nov. 20, 1934INVENT'O' Patented Oct. 27, 1936 PATENT OFFICE PULP PROCESS Adam Hoche,Brooklyn, N. Y.

Application November 20, 1934, Serial No. 753,798 Renewed March 18, 19363 Claims.

This invention relates to cellulose fibre, particularly to theseparation thereof from bodies consisting largely thereof associatedwith undesired natural substances.

5 Those skilled in the art of making cellulose pulp, :that is, theseparation of cellulose libres from bodies consisting largely thereofassociated with undesired or deleterious substances, are fully awarethat the present day processes include many steps, which require costlyequipment, are slow in operation, and, due to the necessary agitation ofthe fibre and the subjection thereof to powerful chemical substances forprotracted periods,

result in a pulp or fibre which is both short and weak. A furtherdisadvantage with present processes is the low yield.

Applicant, realizing the deficiencies in present day processes, afterprotracted study, experimentation, analysis and testing arrived at theconclusion that a proper process for the recovery of cellulose fibres,must be one in which, the fibre is subjected to the least possiblemechanical agitation or handling; to the lowest possible temperature;treated for the shortest possible time; subjected to a chemicalsubstance or substance most active inaction upon the foreign ordeleterious or undesired substances associated with the fibre, and leastactive or injurious to the fibre itself; and, further, that the processshould preferably be such that the number of steps is reduced to aminimum, preferably substantially one, to the end that separation andbleaching be accomplished in one treatment.

With this end in view, applicant has devised a 35 process for theseparation of cellulose fibre from associated undesired naturalsubstances which is, in eiect, a one step process. This process iscarried out without mechanical agitation; at room temperature, save forany increased temperature due to the reacting masses; necessitates anextremely short exposure of the fibre to the chemicals used; includesthe use of chemicals which are extremely active toward the undesired anddelterious substances and comparatively inert, in the concentrationsused, toward the cellulose; and substantially separates the deleterioussubstances and bleaches in one treatment, which completes the processsave for a necessary separation of the chemicals used from the treatedmaterial and a subsequent water wash of the material to remove the lasttraces of chemicals and soluble impurities from the cellulose pulp.

In order to better describe the new process applicant has selected aspecific form of apparatus merely to illustrate the carrying out of theprocess.

In describing the invention in detail and the particular form ofapparatus selected to illustrate the invention, reference is had to theaccompany- 60 ing drawing in which like characters of referencedesignate like parts throughout the several views, and in which:

Figure l is a side elevational view with some parts broken away to moreclearly show the construction, of an apparatus by which applicantsprocess may be carried out; Fig. 2 is a top plan view of the apparatusas shown in Fig. l.

In carrying out the process, applicant selects a suitable cellulosefibre carrying mass, such as wood chips, sisal, hemp, bagasse or thelike, in fact any of the ordinary and well known source materials.

The selected material is placed in a vessel of suitable form, size andmaterial and equipped with the obvious accessories for facilitating thetreatment. in general, any vessel of the general form of a tank issuitable. The material is preferably placed somewhat loosely in thetank, to the end that the treating solution may readily penetrate toevery particle.

In Figure l applicant has illustrated vessels l, 2, 3, 4 and 5 which maybe considered as any ordinary well known type of vessel of the formshown which is formed of an acid resisting material, preferably glass.

Applicantputs into each of the vessels l to 5 inclusive selectedmaterial about up to the line 6.

Each of the vessels is provided with a stopper, as 1, formed with twoorifices therethrough. The stopper of vessel l has a tube 8 of acidresisting material, preferably glass, passed through one of the orificesand la ling and safety tube 9 of similar material pas ed through theother orifice in the stopper 1. Each of the other vessels has a longtube as I0 passing through the stopper of the vesselwhich long tubereaches nearly to the bottom of the vessel; and another short tube ilcomparable with the tube 8 which passes through the orifice in thestopper and terminates shortly below the stopper.

The short tube, as 8, of one vessel is connected to the long tube, asI0, of the next succeeding vessel by any suitable and appropriate meanssuch as by a flexible tube I2 made preferably of an acid resistingmaterial such as caoutchouc or rubber.

- Onto the material of vessel I, applicant flows directly while thestopper 1 is partially removed, or by way of the filling tube 9, asolution of water and nitric acid mixed to a concentration of from 1 to45 Baum and in addition adds a starch or saccharose such as cane sugaror molasses4 thereto. The can sugar is added in the' proportion of about5 pounds'of cane sugar to 1 ton of wood chips, but this may be decreasedto about l pound in some cases and in others increased to 8 poundsdepending upon the quantity of substances in the bre mass capable offorming oxalic acid, or the rapidity to which it is desired for thereaction to proceed.

The contents of vessel I are made exactly in accordance with thedisclosure of my copending application for Pulp process, Serial No.751,255, filed November 2, 1934.

The contents of vessels 2, 3, 4 and 5 are each alike and consist of Woodchips or other suitable fibre bearing mass together with water solutionof sulphuric acid of 1% to 10% concentration.

The reaction between the materials of vessel I starts at ordinary roomtemperature and at ordinary atmospheric pressure. As reaction proceedsthe contents of vessel I become somewhat heated and a certain amount ofdistillation takes place through the tubes 8, I2 and I0. The productsthus distilled issue from the lower end of the tube I and bubble throughthe liquid of vessel 2. As the reaction proceeds there may be furthertransfer from vessel 2 to vessel 3, and from 3 to 4, and from 4 to 5,but usually the major absorption takes place in vessel 2. The reactionin vessel 2 is allowed to proceed until the fibre bearing mass thereinhas been so acted upon, that it is in condition to be water washed,whereupon the contents of vessel 2 are removed, the surplus liquid drawnout by any appropriate means such as by a centrifuge, and then the masswater Washed in any suitable and appropriate manner. In case acentrifuge is used to remove the acid liquor, then the mass may be waterwashed in the centrifuge.

The product obtained is a cellulose fibre of great strength and of acolor such that it requires no bleaching.

The process gives a very high yield of fibre and the fibre is strong andsuitable for use in those processes which require a strong Whitecellulose fibre.

The exact chemical reactions are not, perhaps, thoroughly understood,but it is believed that the reaction in vessel I in which there is adilute solution of nitric acid together with a fibre mass and acarbohydrate, generates oxalic acid and some oxides of nitrogen. It isbelieved that the oxalic acid is the active disintegrating agent andsome passes over from vessel I to vessel 2 and serves to disintegratethe fibre mass so as to separate the cellulose therefrom. At theSametime, the dilute solution of sulphuric acid in vessel 2 tends toform a sugar with some of the substances present in the bre mass andthis sugar reacts with the oxides of nitrogen which bubbles through theliquid to further form an oxalic acid which further acts to disintegratethe fibre mass.

The strength of acid used in vessel I and the strength of acid used invessels 2 to 5 inclusive depends upon the resistance of the materialused.

If the material is very resistant and rapidity is desired, then a strongacid solution is used in vessel I and a strong acid solution in vessels2 to 5, inclusive.

The process is particularly noteworthy because it produces a fibre whichis rich in oxycellulose and is therefore particularly useful 'in themaking of cellulose esters.

The process is inexpensive because only about 5 to of the nitric acid invessel I is consumed by a single treatment of a fibre bearing mass.I

The remainder is recovered by, for example, the separation at thecentrifuge as explained in the application herembefore referred to, andmay be used again by bringing it up to proper strength.

After the material in vessel 2 has been brought to the proper conditionfor washing the connection from vessel I may be made directly to vessel3; and after the material in vessel 3 has been suitably treatedconnection in the same manner may be made to vessel 4 and then to vessel5. In case connection is made directly from vessel I to vessel 3,applicant would connect a fresh vessel with vessel 5, that is, applicantprefers to always have at least 4 vessels, as 2 to 5 inclusive,connected to a vessel such as I in which the reaction is proceeding, sothat every last particle of distillate is absorbed even if the adjoiningvessel as 2 has practically completely reacted so that a large amount ofdistillation takes place from 2 to 3.

This process may be considered as an extension of the process of myprior application hereinbefore referred to as the vessel I is used tocarry out the process exactly as described in my prior application. Theremaining vessels are used to save and preserve that which otherwisewould be a loss in carrying out the process in vessel I.

Having described the principle and mode of operation of my invention anda .particular application thereof and a specific apparatus by which myprocess may be carried out, I desire to have it understood that thespecific apparatus selected is merely illustrative and does not exhaustthe possible apparatus forms by which the underlying principles of myinvention may be exemplified.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is:

1. A process of separating cellulose fibre from a fibre mass admixedwith undesired other natural substances and simultaneously bleaching itwhich consists in substantially covering the mass with a water solutionof 1% to 10% of sulphuric acid, bubbling through that solution productsdistilled from a reaction taking place between a fibre mass admixed withundesired other natural substances and dilute nitric acid, and thenseparating the liquids from the solids and washing with water untilsubstantially acid free.

2. A process of separating cellulose fibre from a fibre mass admixedwith undesired other natural substances and simultaneously bleaching itwhich consists in substantially covering the mass With a water solutionof 1% to 10% of sulphuric acid, bubbling through that solution productsdistilled from a reaction taking place between a fibre mass admixed withundesired other natural substances, dilute nitric acid and substancesselected from the group comprising saccharose, starch, and molasses, andthen separating the liquids from the solids and washing with water untilsubstantially acid free.

3. A process of separating cellulose bre from a fibre mass admixed withundesired other natural substances and simultaneously bleaching it whichconsists in substantially covering the mass with a water solution of 1%to 10% of sulphuric acid, bubbling through the solution productsdistilled from a reaction taking place between a fibre mass admixed withundesired other natural substances, dilute nitric acid of aconcentration from 1 to. 45 Baum at room temperature and at ordinaryatmospheric pressure with absence of agitation and about 1 to 8 poundsof a substance selected from the group comprising cane sugar, starch andmolasses to two thousand pounds oi' said bre mass, and then separatingthe liquids from the solids and washing with water until substantiallyacid free.

ADAM HOCHE.

